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1981 Rear End Suspension

Silver81Vette

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Joined
Jun 12, 2007
Messages
23
Location
Wheeling, West Virginia
Corvette
1981 Silver T-Top (St. Louis Car)
How does one new Corvette owner of a 1981 C3 know that the rear suspension needs attention? I have noticed that the rear end of the car rides awfully low, and sometimes it feels like it "bottoms out" I just ordered a set of KYB shocks for it, and it goes in for new Goodyear Eagles and an alignment here this week....Any suggestions??

Thanks!!! ;help
 

bill81vette

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Joined
Jan 17, 2004
Messages
4,320
Location
Troy,NY
Corvette
1981 dark blue metallic
the 81's do have a mono spring.I have noticed on mine the back end does lower when it is put into gear....but I haven't bottomed out.
you could have the back end looked at to make sure all the grommets are good and everything is intact.BUT if someone looks at it have them show you where the problem.
or back it up on some ramps and crawl under it your self and take a look around underneath it...
 

Vette79

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Jan 23, 2007
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1,392
Location
Millersville, MD
Corvette
1979 L-48 Black Coupe
A corvette ride is an acquired taste to begin with. I had my rear end done 7 months ago. Shocks, mono spring and bushings. You should take it to someone who knows corvettes and who can give you a professional opinion. How long has it been since these items have been replaced? You have already ordered new shocks but if the vette rides awefully low as you had mentioned then my guess would be the mono spring. Do both at the same time...
 

MFPvette80

Active member
Joined
Mar 19, 2005
Messages
35
Location
Le Roy, NY
Corvette
1980 metallic red
My 1980 was equpped with the Gymkhana suspension from the factory, and later replaced with a 7 leaf spring. I also notice the back end dropping when it's put into gear. Why is that?
 

Evolution1980

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Cleveland, Ohio
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ZZ4, 700R4, Steeroids rack & pinion, VB&P Brakes
My 1980 was equpped with the Gymkhana suspension from the factory, and later replaced with a 7 leaf spring. I also notice the back end dropping when it's put into gear. Why is that?
1) Almost all rear-wheel drive ("RWD") cars 'squat' when you put 'em in gear because of the torque being applied to the rear end. That's normal and has been since as long as I can remember. The rear end squats and the front end lifts. Ever hear of the term "Wheelie bars"? Think of dragsters...

2) A 7 leaf spring may not be enough in the rear. I think it comes down to preference in ride quality -vs- handling. Some people like more leafs back there for a stiffer ride. Other's don't. However, the more leafs, the longer they also take to settle. I think mine has 9 leafs and took YEARS to finally reach a reasonable ride height. And that included longer bolts to let the body sit more parallel to the ground. Someday I'll probably switch to a single composite leaf spring.
 

Evolution1980

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Cleveland, Ohio
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ZZ4, 700R4, Steeroids rack & pinion, VB&P Brakes
How does one new Corvette owner of a 1981 C3 know that the rear suspension needs attention?
The rear should sit a bit higher when the car is in Park/Neutral.
When the car is put in gear, the rear end should squat just enough that it's almost parallel to the ground. If it's a wee bit higher in the back still, that's OK because when you're on the gas, it will level out more.

If putting the car in drive causes the rear end to sag below level with the front, then you need to start a fixin' things.

Below is my estimate of what the approximate correct ride height should be for the car in Park/Neutral. Notice it's ever so slightly higher in the rear.
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MFPvette80

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Joined
Mar 19, 2005
Messages
35
Location
Le Roy, NY
Corvette
1980 metallic red
I never did look at how the car sits in drive. The squat is a RWD phenomeneon I agree, but on the vette it's very pronounced.

Not get off-topic to much but another characteristic of the suspension system seems to be the rear wheels being off camber (tilted inward at the top). I've seen this on lots of vettes, and compared to my front wheels the rears tilt in by an inch and a half while sitting still. I'm getting an alignment soon, but wondered if this is normal. I would assume tire wear would be abnormal also.
 

Evolution1980

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ZZ4, 700R4, Steeroids rack & pinion, VB&P Brakes
The squat is a RWD phenomeneon I agree, but on the vette it's very pronounced.
...only if the rear end parts need adjusting or replacement. And/or the more torque you have, the more squat induced.

Not get off-topic to much but another characteristic of the suspension system seems to be the rear wheels being off camber (tilted inward at the top). I've seen this on lots of vettes, and compared to my front wheels the rears tilt in by an inch and a half while sitting still. I'm getting an alignment soon, but wondered if this is normal. I would assume tire wear would be abnormal also.
It's normal in at least two cases that I can think of.
1) If the rear suspension is worn or needs adjustment
2) If the alignment is specifically set that way for high speed runs. If I recall correctly ("IIRC"), the tires will right themselves up as their revolutions increase.

Most of the time, the reason is squarely on #1.
 

MFPvette80

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Joined
Mar 19, 2005
Messages
35
Location
Le Roy, NY
Corvette
1980 metallic red
Good feedback. The more noticable squat may be due to the motor puting out nearly twice the HP as the original equipment set-up. I'll know more about the rear-end condition after the alignment. When I replaced the half-shaft universals last year everything looked good though. Unfortunately, the only vette I've ever worked on or drove is the one in my garage. There's no real good point of reference when I describe the vehicle's condition.

I believe that the rear wheels must align better at speed, since that would explain the absence of unusual tire wear.
 

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